JP3663461B2

JP3663461B2 - Frequency selective spatial improvement system

Info

Publication number: JP3663461B2
Application number: JP24599697A
Authority: JP
Inventors: チョイピュン
Original assignee: 3S Tech Co Ltd
Current assignee: 3S Tech Co Ltd
Priority date: 1997-03-13
Filing date: 1997-08-28
Publication date: 2005-06-22
Anticipated expiration: 2017-08-28
Also published as: DE69737087D1; JPH10271600A; DE69737087T2; EP0865226B1; EP0865226A2; HK1016010A1; EP0865226A3; US6587565B1

Description

【０００１】
【発明の属する技術分野】
本発明は、左、右のスピーカを利用してステレオ信号から３次元イメージの音を再現するにあたって、音の空間感を拡大すると共に、背景音を強調してライブ効果を導出する３次元ステレオイメージプロセッシングに関する技術である。
【０００２】
【従来の技術】
ステレオサウンド信号の空間感を拡大するための従来の技術としては、米国特許第４，７４８，６６９号に提示された「STEREO ENHANCEMENT SYSTEM（ステレオエンハンスメントシステム）」や、米国特許第４，８６６，７７４号に提示された「STEREO ENHANCEMENT AND DIRECTIVITY（ステレオエンハンスメントアンドディレクティヴィティ）」などがある。上記米国特許第４，７４８，６６９号および第４，８６６，７７４号には、ステレオイメージの拡張及び音の方向性と空間性を拡大するための技術が開示されている。これらの従来技術では、左側チャンネル信号（Ｌ）と右側チャンネル信号（Ｒ）からＬ＋Ｒ信号及びＬ−Ｒ信号を得て、これらの信号の周波数、位相、利得（ＧＡＩＮ）を適切に変化させた後、最終的に左右のマトリックス段で演算して、結果的に音の空間感と方向性と強調するようにしている。
【０００３】
この先行技術では、Ｌ＋Ｒ信号およびＬ−Ｒ信号を処理する処理手段が必ず必要であり、ステレオイメージを形成するためのＬ−Ｒ信号をフィルタ、利得調整回路及び各種の演算回路に通し、その結果として立体感のあるサウンドを得るようにしている。しかしながら、この従来の方法ではＬ−Ｒ信号を周波数的に処理して、左側と右側のチャンネルでそれぞれ演算処理するように構成されているため、ステレオ信号の差成分の量が極めて小さくなってしまう。また、主に高域帯に信号が分布するため、音声帯域や低域の信号が抜けた状態になるという問題がある。
【０００４】
ここで、Ｌ＋Ｒの信号を別の経路を介して最終マトリックス段に追加することによって、左、右のスピーカの中心位置で音が再生されるようになり、均衡のとれたサウンドが再現できる。しかし、このような信号処理方式では、元のステレオ信号の左右の音をＬ＋Ｒ、及びＬ−Ｒの信号処理を行った上で、周波数的に補強して最終マトリックス段で再配置するようにしているため、音の立体感は多少得られるが、原音損失の影響が大きくなる。特にＬ＋Ｒ信号（モノフォニック信号）を付加することによって、ソフト（ＳＯＦＴ）によってはステレオ感をなくしてしまうといった逆効果が生じる。また、元のステレオ信号が左右に分離されなくなり、音の明瞭性が劣化し、既存のステレオ効果に比べて、音質や左右の音の分離の度合いが劣るといった現象が起こる。
【０００５】
一般的な３次元イメージ回路の特性上、立体処理回路に信号を通すと、音声帯域の信号が減衰する。また、元のステレオ信号を再処理することによって原信号に損失が生じるため、このような音を長時間聴取すると不快感が生じることがある。また、各種のフィルタや位相シフト等によって原音が再処理される過程で、信号間の相互干渉や歪曲が起こるため、上述した従来の技術では、臨場感のある音は再現できるが、原音の損失は避けることができず、したがって、クラシック音楽などを再生する場合、ほとんどその原音を利用することができない状態になる。
【０００６】
【発明が解決しようとする課題及び手段】
本発明によれば、原音の損失を最小限に抑えることができると共に、３次元イメージ感を向上させることができる。また、音盤製作時の最初のミキシング過程で不可避的に生じる背景音の量の減少を、再生過程で補強してライブな生動感のある音を再生することができる。本発明の技術では、上述の先行技術のようにＬ＋Ｒ信号とＬ−Ｒ信号を様々な回路で処理することなく、チャンネル信号を重視して再処理する回路構成が採用されている。したがって、音場の変化を最小限に抑えると共に信号対雑音比およびＴＨＤ（ＴｏｔａｌＨａｒｍｏｎｉｃＤｉｓｔｏｒｔｉｏｎ）を減らして原音の損失を少なくし、更に音の方向性と空間性、および生動感を拡大することができる。
【０００７】
通常、中低価格のオーディオ機器で音響信号を再生する場合、アンプやスピーカの品質あるいは性能が制限されるため、低域、中域、高域の全周波数帯にかけて美麗な音を再生することは不可能である。しかし、本発明を適用することによって、このようなアンプやスピーカなどの性能上の制約をある程度解消することができる。すなわち、本発明では、低域帯では原信号を中心として利得特性をあげるようにし、中域帯は元信号と差信号を５０対５０程度で構成し、音の方向性と空間感を表現する領域である高域帯では差信号を中心に利得を上げることによって、自然な音を再構成するようにしている。したがって、性能上の制限を受けざるを得ないような中、低級機でも音響信号の再現特性を改善することができる。
【０００８】
すなわち、本発明のシステムは、ステレオ信号を処理するのに適した相互に対称的な回路構成を有し、左右のチャンネルの音の差を利用して音の空間性を上げると共に、回路構成を簡潔にして信号対雑音特性の劣化を防止して、価格に対する装置の性能を大きくし向上させた新しい概念のサラウンドシステムである。
【０００９】
後述する通り、本発明では、左右のチャンネル信号から空間性イメージを周波数的側面で抽出する空間性助成部と、元の音の中域と低域を補強するための周波数帯域補強部と、チャンネルマトリックス手段とを主要構成とする。
【００１０】
【発明の実施の形態】
図１は、本発明にかかる周波数選択的空間感向上システムの基本的な構成（第１の実施形態）を示すブロックダイアグラムである。尚、このシステムは、ステレオ入力信号から３次元イメージステレオ信号を作るプロセッサに適用する。図１に示すように、本実施形態のシステムは、左右の入力信号（Ｌ−ｉｎ）（Ｒ−ｉｎ）をそれぞれ入力して音の空間性と方向性を強調する空間性助成部（３０）（４０）と、左右の入力信号をそれぞれ入力して元音の中域と低域を補強する帯域補強部（５０）（６０）と、上記空間性助成部（３０）（４０）の出力信号と、帯域補強部（５０）（６０）の出力信号、及び左右のチャンネル信号をマトリックス処理するチャンネルマトリックス段（７０）（８０）とを、左右の信号ラインにそれぞれ具えている。
【００１１】
このような構成を持つ本発明のシステムでは、左右の入力信号（Ｌ−ｉｎ）（Ｒ−ｉｎ）がバッファ（１０）（２０）を通って各回路に入力されるように構成されている。ここで信号入力ラインにバッファ（１０）（２０）を設けた理由は、入力側のインピーダンスを高くして信号伝達間における信号の減衰を減らして、周波数特性面における信号の劣化を補強すると共に、次段の信号がいろんな経路で処理されることによって信号が劣化することを防止するためである。
【００１２】
図１に示すように、入力信号（Ｌ−ｉｎ）（Ｒ−ｉｎ）は、バッファ（１０）（２０）を経て、音の空間性及び方向性を強調する左右の空間性助成部（３０）（４０）と、元の主チャンネル信号の中域帯と低域帯を補強する帯域補強部（５０）（６０）にそれぞれ入力される。これらの空間性助成部（３０）（４０）の出力と帯域補強部（５０）（６０）の出力は、更に左右のチャンネルマトリックス部（７０）（８０）に入力される。また、入力信号（Ｌ−ｉｎ）（Ｒ−ｉｎ）の一部をチャンネルマトリックス部（７０）（８０）に直接入力させるようにしている。
【００１３】
空間性助成部（３０）（４０）では音の方向性と空間性を作り出すためのＬ’とＲ’信号を形成する。ここで空間性助成部（４０）の出力信号Ｌ’を右側のマトリックス部（８０）へ、また空間性助成部（３０）の出力信号Ｒ’を左チャンネルマトリックス（７０）に入力し、ここでＬ−Ｒ’とＲ−Ｌ’の演算がそれぞれ行われる。
【００１４】
帯域補強部（５０）（６０）は元のチャンネル信号の中域と低域を補強するためのものであり、ここで信号Ｌ”とＲ”が形成される。このＬ”とＲ”信号は、左右のチャンネルマトリックス（７０）（８０）にそれぞれ入力され、上述のＬ−Ｒ’とＲ−Ｌ’の演算結果に加算される。すなわち、左右のチャンネルマトリックス（７０）（８０）は前段の空間性助成部（３０）（４０）の出力（Ｌ’）（Ｒ’）と帯域補強部（５０）（６０）の出力（Ｌ”）（Ｒ”）と、主チャンネル信号（Ｌ）（Ｒ）とをマトリックス演算するよう構成されており、左側チャンネル（Ｌ−ＯＵＴ）ではＬ−Ｒ’＋Ｌ”の形態の信号を、右側チャンネル（Ｒ−ＯＵＴ）ではＲ−Ｌ’＋Ｒ”形態の信号が最終的に、出力される。
【００１５】
ここで空間性助成部（３０）（４０）は高域通過フィルタの特性を持ち、帯域補強部（５０）（６０）は低域通過フィルタの特性を持つ。これらのフィルタが中域帯でほとんど１に近い利得を持つように構成することによって、中域帯の信号が左右完全に同一である場合は、Ｌ＝Ｌ’＝Ｌ”＝Ｒ＝Ｒ’＝Ｒ”となる。したがって、マトリックス部（７０）（８０）でＬ−Ｒ’＋Ｌ”、Ｒ−Ｌ’＋Ｒ”の演算を行うことによって、左側チャンネル（Ｌ−ＯＵＴ）にＬ＝Ｒ＝１が出力し、右側チャンネル（Ｒ−ＯＵＴ）にＲ＝Ｌ＝１が出力する。また、左右の中域帯の信号に差がある場合は、左側チャンネル（Ｌ−ＯＵＴ）にＬ＋（Ｌ”−Ｒ’）が出力し、右側チャンネル（Ｒ−ＯＵＴ）にＲ＋（Ｒ”−Ｌ’）が出力する特性を持つ。このように構成することによって、中域帯では左右の信号がどんな形態であっても、その信号がそのまま維持されて出力されることになる。
【００１６】
また、低域帯では、Ｒ'とＬ'成分が低い利得を持つことになるため、上記のＬ＋（Ｌ”−Ｒ’）とＲ＋（Ｒ”−Ｌ’）の演算を行うにあたって、信号の主成分であるＬ＋Ｌ”とＲ＋Ｒ”成分が相対的に大きくなる。従って、低域帯では元のチャンネル信号が強調されて出力される特性を持つ。
【００１７】
一方、音の空間感と方向性を左右する高域帯では、帯域補強部（５０）（６０）の出力であるＬ”とＲ”の利得が小さく、空間性助成部（３０）（４０）の出力であるＲ’とＬ’の利得が１に近い。したがって、Ｌ＋（Ｌ”−Ｒ’）とＲ＋（Ｒ”−Ｌ’）の演算を行うにあたって、Ｌ−Ｒ’とＲ−Ｌ’が中心成分になるので結果的に音の空間感と方向性が増大される。
【００１８】
すなわち、本発明では、音の周波数帯域を大きく３等分して、低域帯信号では主チャンネルの信号を補強して、中域帯では主チャンネルの信号をそのまま維持し、高域帯では相互の減算量を大きくすることによって、低、中、高域帯のすべての領域に亘って音の均衡を取りながら、全体的に音の空間感と方向性が向上するように構成されている。
【００１９】
図２は、本発明の周波数選択的空間感向上システムの空間性助成部の詳細な構成を示す図であり、図２（ａ）は空間性助成部の回路構成を示す図、図２（ｂ）はその特性グラフである。空間性助成部は左右のチャンネルにそれぞれ設けられており、音の空間性と方向性および背景音を強調するためのＲ’とＬ’信号を作る回路構成を有する。
【００２０】
その基本的な概念は、各チャンネル信号の音声周波数を中心にして高域側に該当する信号成分を周波数選択的に通過させてＲ’、Ｌ’信号を作り、マトリックス段にて相対する主チャンネル信号からこれを減算することで音の３次元イメージ成分の信号を導出することである。一般的なステレオ信号は、中域帯及び低域帯では、左右のチャンネル信号に共通成分が多く、実際に音を左右に分離するステレオ成分、及び三次元イメージ成分は高域帯に多く含まれている。したがって、各チャンネルにおいて音性周波数を中心として高域側に該当する信号を周波数選択的に通過させて相対する主チャンネル信号からこれを減算することで３次元イメージ成分の信号を導出することができる。
【００２１】
図２（ａ）に示す通り、空間性助成部（４０）はコンデンサ（Ｃ４１）と抵抗（Ｒ４１）でできた回路構成を持ち、高域通過フィルタを構成している。ここでコンデンサ（Ｃ４１）と抵抗（Ｒ４１）の時定数に応じて通過域と遮断域の周波数帯の利得特性を調整することができる。また、この時定数に応じて臨場感と中域音も調整することができる。この回路は後段のマトリックス回路で主チャンネル信号から減算するためのＲ’成分とＬ’成分を作るために設けられており、中、高域帯での利得を１にして、低域帯で遮断周波数を持つ高域通過フィルタを構成する。図２（ｂ）に、空間性助成部４０の出力の一例の周波数特性を示す。
【００２２】
図２（ａ）に示す空間性助成部４０の回路を構成する抵抗（Ｒ４１）とコンデンサ（Ｃ４１）の時定数を調整することで３次元ステレオイメージ信号の量を自由に調整することができる。また、これらの素子の時定数を調整することによって音の空間性を調整して各種の３次元イメージの形態を構築することができる。
【００２３】
空間性助成部（４０）後段に設けられている抵抗（Ｒ４２）は右チャンネルマトリックス（８０）のマトリックス演算回路の因数を決定して、右チャンネルマトリックス（８０）でＲ−Ｌ’＋Ｒ”を演算する際の−Ｌ’演算機能を実行するためのものである。
【００２４】
図３は、本発明のシステムに用いる帯域補強部の詳細を示す図であり、図３（ａ）は帯域補強部の回路の構成を示す図、（ｂ）はその特性を示すグラフである。帯域補強部は、マトリックス段で行われる減算作用（Ｌ−Ｒ’）によって減衰する主チャンネル信号の中、低域の成分を補強する機能を有し、低域通過フィルタ特性を持つ。前述のＲ’信号成分は中域、高域帯で利得が１に近いため、（Ｌ−Ｒ’）の演算を行うと相対的に中音が減衰するので、これを補強して音の中心成分をなくさないようにするための構成である。
【００２５】
図３（ａ）に示すように、帯域補強部５０は、抵抗（Ｒ５１）とコンデンサ（Ｃ５１）とで構成されている。この抵抗（Ｒ５１）とコンデンサ（Ｃ５１）の時定数に応じて低域通過フィルタの遮断周波数が決定される。本発明では、高域帯で遮断周波数を持つ低域通過フィルタを構成するようにした。音声帯域が１ｋＨＺ帯なので、ここで、音声帯域すなわち中域帯で約１の利得をもたせ、低域帯でも１の利得を持たせるようにすることによって主チャンネル信号の音声帯及び低域帯を補強することができる。
【００２６】
回路構成上、抵抗（Ｒ５１）とコンデンサ（Ｃ５１）は、中域、低域を補強するための低域通過フィルタである。帯域補強部５０の後段に左チャンネルマトリックス（７０）に接続させて設けた抵抗（Ｒ５２）は、左チャンネルマトリックス（７０）でＬ−Ｒ’＋Ｌ”を演算する際のＬ”信号成分の演算因数を決定するためのものである。図３（ｂ）に、帯域補強部５０の出力の一例の周波数特性を示す。
【００２７】
図４は、本発明のシステムに用いるマトリックス手段の詳細な構成を示す回路図である。このマトリックス回路では、オペアンプ（Ｕ７１）の加算及び減算機能をすべて利用して、主チャンネル信号と帯域補強部（５０）の出力信号、そして空間性助成部（３０）の出力信号を加算及び減算するようにした。すなわち、主チャンネル信号Ｌと帯域補強部（５０）の出力信号である信号Ｌ”をオペアンプ（Ｕ７１）の非反転入力（＋）に入力させ、空間性助成部（３０）の出力信号Ｒ’を反転入力（−）に入力させている。
【００２８】
この左チャンネルマトリックス（７０）の演算因数は抵抗（Ｒ７１）（Ｒ７２）（Ｒ７３）（Ｒ７４）で決まる。これらの抵抗をすべて同じ値にするとオペアンプ（Ｕ７１）の加減算構造式によってチャンネルマトリックス（７０）の出力はＬ＋Ｌ”−Ｒ’になる。また、マトリックス（７０）と同じ構成を持つ右チャンネルマトリックス（８０）の出力はＲ＋Ｒ”−Ｌ’になる。すなわち、各信号の加減算因数はすべて１に設定される。また、用途に応じて抵抗（Ｒ７１）（Ｒ７２）（Ｒ７３）（Ｒ７４）の値を変えて設定すれば適切な因数を構成することができる。
【００２９】
このマトリックスの加減算の因数の最適値は、実際のステレオ装置を動作させたときの人間の聴取特性等によって異なり、本発明の左側出力Ｌ＋Ｌ”−Ｒ’と右側出力Ｒ＋Ｒ”−Ｌ’はその一例として見ることができる。すなわち、上記、マトリックス関係式は供給電源やその他の適用条件に応じて様々な因数の配列が考えられ、状況に応じて上記の配列以外の値をとることができる。また、マトリックス回路（７０）（８０）に抵抗を追加したり削除することで、同様に利得因数を調整することもできる。
【００３０】
尚、空間性の効果を一層上げるために、図５に示すように空間性助成部（４０）と帯域補強部（５０）の後段とチャンネル信号ラインに利得調整用回路（１１０ａ、１１０ｂ、１１０ｃ）を設けて、空間性助成部（４０）の出力、帯域補強部（５０）の出力と、チャンネル信号との相互利得を外から調整できるようにしても良い。あるいは、この構成に替えて、図６に示すように、マトリックス回路（７０）（８０）に可変抵抗（Ｒ７５）を設けて相互利得を外から調整するようにしても良い。このように、マトリックス回路（７０）（８０）の前段に利得調整素子を設けたり、マトリックス回路の抵抗を調整することによって、空間性助成部（４０）および帯域補強部（５０）の出力と、各チャンネル信号との相互利得を外から調整できるようにすれば、聴音の状況、あるいは電源等の周辺機器の状態などに応じて、各帯域の利得を適宜調整することによってより高品質の音を得ることができる。
【００３１】
図７は、本発明のシステム全体の動作を各信号の周波数−利得特性によって示すグラフである。ここでは、左チャンネルマトリックス（７０）で行われる演算を例にとって説明する。
【００３２】
図７（ａ）は、主信号である左チャンネル信号（Ｌ）の周波数特性を示すグラフである。この信号Ｌはバッファ（１０）を通過して帯域補強部５０とマトリックス部７０へそのまま入力される。この信号Ｌは可聴周波数全帯域に亘って利得が１である信号特性を持つ。
【００３３】
図７の（ｂ）は帯域補強部（５０）、すなわち低域通過フィルタの出力信号Ｌ”の周波数特性を示すグラフである。この信号は中域及び低域帯では１の利得を持ち、１０ｋＨＺ以上で漸次利得が減少する特性を持つ。
【００３４】
そして図７（ｃ）は空間性助成部（３０）の出力信号Ｒ'の周波数特性を示すグラフである。この信号Ｒ’は主チャンネル信号の右チャンネル信号から中高域帯以上の周波数成分を取り出して、後段の左マトリックス部（７０）で主チャンネルの左チャンネル信号から減算するためのものである。空間性助成部（３０）は、約１００ＨＺ以上を通過域とする高域通過特性を持っており、したがって、この信号Ｒ’は１００ＨＺ以上の帯域で利得が約１である周波数特性を持つ。
【００３５】
なお、上記空間性助成部（３０）と帯域補強部（５０）は外部から抵抗値を可変にできるように構成して、フィルタの時定数を変えて遮断周波数を任意に調整できるようにしてもよい。また、大量に生産する場合は、時定数を固定にすることもできる。
【００３６】
図７（ｄ）は、左右のチャンネルの信号の共通成分の周波数特性を示すグラフである。図７（ｄ）に示すように、左右のチャンネル信号の共通成分には音声帯域すなわち中域帯を含んだ低域帯の信号成分が多く含まれている。すなわち、一般的なステレオ音源の特性上、音声帯域と低域では左右チャンネルともに共通成分が多く分布しているので、この帯域ではＬ＝Ｒの性格を持つことが多い。左チャンネルマトリックス（７０）の最終演算式がＬ＋Ｌ”−Ｒ’なので、ここにＬ＝Ｒ＝１を代入すると低域ではＬ＝Ｌ”＝１であり、Ｒ'信号の分布が小さくなる。その結果、低域では利得が２となり、漸次小さくなる構成となる。また、中域ではＬ＝Ｌ”＝Ｒ’＝１なのでほとんど利得１の値を維持することができる。
【００３７】
このように構成することによって、低域では元のチャンネル信号を強調して音を再現し、中域帯では左、右側チャンネル信号の類似性の有無によって多少の利得差はあるが、中域帯すなわち音声信号成分の利得を維持することができるようになる。すなわち、元のチャンネルの低域を強調して再現するとともに、中域帯の音はそのまま維持する効果を同時に成し遂げられる。
【００３８】
図７（ｅ）は空間性の領域を左右する中、高域帯の信号の出力特性、すなわち左右のステレオ信号の差成分の周波数特性図である。一般的に、ステレオ音源の特性や、耳の聴覚特性上、音の空間感とか方向性を認識する領域は、中、高域帯にある。ここでマトリックス段の最終演算式がＬ＋Ｌ”−Ｒ’であり、上述した通り、中域帯では共通成分が多いのでＬ＝Ｌ”＝Ｒ’＝１と仮定すると、その演算結果はほとんど１に近くなり中域すなわち音声域はそのまま維持される。一方、高域帯では、帯域補強部の出力のＬ”成分が少ないため、信号成分は主にチャンネル信号Ｌと空間性助成部の出力Ｒ’との差成分、Ｌ−Ｒ’成分によって構成されるようになる。したがって、中域すなわち音の中心部分をそのまま維持しながら、音の空間感とか方向性を決定する領域である高域帯で差成分が占める割合が大きくなるので、空間感あるいは背景音を拡大した効果を導出できる。
【００３９】
本発明では、結果的に、中、低域では元の音（音声域）維持し、補強すべく作用して、中、高域では音の空間感を拡大すると共に、元の音（音声域）は維持するようにして、全周波数帯域に亘って均衡を取ると同時に音場感を拡大するといった理想的な結合を得ることができる。
【００４０】
図８は、本発明にかかるシステムの第２の実施形態の全体の構成を示すブロックダイアグラムである。図８に示すように、第２の実施形態ではマトリックス段（７０）（８０）でシステム全体の利得を上げた後、このマトリックス段（７０）（８０）後段に帯域補強部（９０）（１００）を設けて特定の周波数帯域を補強するようにした。
【００４１】
図９は、本発明にかかるシステムの第２の実施形態のマトリックス段の後段の構成を示すブロック図である。図９（ａ）はこの帯域補強部の詳細な回路構成を示す図、及び図９（ｂ）はその特性を示すグラフである。マトリックス段７０，８０で行われるマトリックス演算により、低、中、高域に亘って適切な音の均衡をとりつつ臨場感のある音の再生処理を行うことができるが、本例では、例えば、映画のソフトと共に用いられ、低域が重視される特定のソフトにも対応できるように、マトリックスの後段に更に第２の帯域補強部（９０）を設け、マトリックス段での信号処理結果に再度フィルタリング処理をすることによって特定の周波数帯域を補強するようにしたものである。この第２の帯域補強部（９０）（１００）にはいろんな回路を適用することができる。図９（ａ）に示すような抵抗とコンデンサで構成された受動回路や、またはオペアンプと受動素子で構成された能動回路で構成することもできる。
【００４２】
本発明の第２の実施の形態では、第２の帯域補強部（９０）を、抵抗（Ｒ９１）（Ｒ９２）とコンデンサ（Ｃ９１）でなる受動フィルタで構成している。右側チャンネルの帯域補強部（１００）の構成も同一である。図９（ｂ）に示す特性グラフからわかるように、このフィルタ構成によれば、通過域の利得が１であり遮断域の利得がＲ９２／（Ｒ９１＋Ｒ９２）になるので、前段のマトリックス回路の出力の利得因数を上げた後、この帯域補強部（９０）（１００）を通して出力するようにすれば低域帯を補強することができ、また中域及び高域帯の利得を調整することもできる。また、必要に応じて能動回路を構成して特定の帯域の利得特性を独立して調整することもできる。
【００４３】
図１０は、本発明にかかるシステムの第３の実施の形態の構成を示す図である。この第３の実施の形態では、回路の簡略化を図るため帯域補強部（５０）（６０）を設けずに左右の各チャンネルからの信号をチャンネルマトリックス（７０）（８０）に入力させて利得を上げて帯域補強部（５０）（６０）の代わりをするように全体の回路を構成した。ただし、空間性助成部（３０）（４０）の回路的役割は他の例と同様である。
【００４４】
本発明のシステムの全体的な動作において、低域では元のチャンネル信号を強調するとともに、中域帯では元の信号をそのまま維持する効果をあげ、更に高域帯で臨場感及び方向性を上げる効果を同時に得ることができる。なお、必要があれば、原音の種類に応じて特定帯域を補強するように構成することもできる。本発明は、ステレオ信号から３次元イメージの音を再現するものであればどのような装置にも適用することが可能である。また、音響信号の再生時のみならず、記録時にも本発明のシステムを適用することができる。
【００４５】
【発明の効果】
本発明によれば、元のステレオ信号に対して適切に回路を設けることによって、最適な３次元立体音響を得ることができる。本発明のサラウンド回路方式によれば、特定帯域の音を維持すると同時に、空間感を拡大することができる。さらに今までのサラウンド方式で見られなかった背景音を再生する効果が得られるとともに、フィルタカーブ特性に従って信号再生のダイナミックレンジを増強できるようにした。
上記の標準的な回路を用いて、適用状況に応じて回路を構成する素子の時定数をわずかに調整することによって、音源の様々な条件に合致した音場効果及び背景音拡大効果を得ることができる。
【図面の簡単な説明】
【図１】本発明の基本構成（第１の実施形態）を示すブロックダイアグラムである。
【図２】図２（ａ）は本発明の空間性助成部の構成を示す詳細な回路図、及び（ｂ）はその特性グラフである。
【図３】図３（ａ）は本発明の帯域補強部の構成を示す詳細な回路図、及び（ｂ）はその特性グラフである。
【図４】本発明のマトリックス部の構成を示す詳細な回路図である。
【図５】図１に示す本発明のシステムの変形例を示す図である。
【図６】図１に示す本発明のシステムの他の変形例を示す図である。
【図７】本発明のシステムの周波数特性利得を示す図である。
【図８】本発明の第２の実施の形態の全体の構成を示す回路図である。
【図９】図７（ａ）は本発明の第２の実施の形態を示す詳細な回路図、及び（ｂ）はその特性グラフである。
【図１０】本発明の第３の実施の形態の構成を示す図である。
【符号の説明】
１０，２０バッファ
３０，４０空間性助成部
５０，６０帯域補強部
７０左チャンネルマトリックス
８０右チャンネルマトリックス
９０，１００帯域増強部[0001]
BACKGROUND OF THE INVENTION
The present invention uses a left and right speaker to reproduce a sound of a three-dimensional image from a stereo signal, and expands the spatial feeling of the sound and enhances the background sound to derive a live effect. Technology related to processing.
[0002]
[Prior art]
Conventional techniques for expanding the spatial feel of stereo sound signals include “STEREO ENHANCEMENT SYSTEM” presented in US Pat. No. 4,748,669 and US Pat. No. 4,866,774. There is “STEREO ENHANCEMENT AND DIRECTIVITY” presented in the issue. U.S. Pat. Nos. 4,748,669 and 4,866,774 disclose techniques for expanding a stereo image and expanding sound directionality and spatiality. In these prior arts, after obtaining the L + R signal and the LR signal from the left channel signal (L) and the right channel signal (R), and appropriately changing the frequency, phase, and gain (GAIN) of these signals. Finally, the calculation is performed in the left and right matrix stages, and as a result, the spatial feeling and directionality of the sound are emphasized.
[0003]
In this prior art, processing means for processing the L + R signal and the LR signal is indispensable, and the LR signal for forming a stereo image is passed through a filter, a gain adjustment circuit, and various arithmetic circuits, and as a result. I try to get a three-dimensional sound. However, this conventional method is configured to process the LR signal in frequency and perform arithmetic processing on the left and right channels, respectively, so that the amount of the difference component of the stereo signal becomes extremely small. . In addition, since the signal is distributed mainly in the high frequency band, there is a problem that the voice band and the low frequency signal are lost.
[0004]
Here, by adding the L + R signal to the final matrix stage via another path, the sound is reproduced at the center positions of the left and right speakers, and a balanced sound can be reproduced. However, in such a signal processing method, the left and right sounds of the original stereo signal are subjected to L + R and LR signal processing, and are then reinforced in frequency and rearranged in the final matrix stage. Therefore, the three-dimensional effect of the sound can be obtained to some extent, but the influence of the loss of the original sound is increased. In particular, by adding an L + R signal (monophonic signal), the reverse effect of eliminating the stereo effect depending on the software (SOFT) occurs. In addition, the original stereo signal is not separated into left and right, sound clarity is deteriorated, and a phenomenon occurs that the sound quality and the degree of separation of left and right sounds are inferior to the existing stereo effect.
[0005]
Due to the characteristics of a general three-dimensional image circuit, when a signal is passed through a three-dimensional processing circuit, the signal in the audio band is attenuated. In addition, since the original signal is lost by reprocessing the original stereo signal, discomfort may occur when such a sound is listened to for a long time. In addition, mutual interference and distortion between signals occur in the process where the original sound is reprocessed by various filters and phase shifts, etc., so that the conventional technology described above can reproduce a realistic sound, but the loss of the original sound Therefore, when playing classical music or the like, the original sound can hardly be used.
[0006]
[Problems and Means to be Solved by the Invention]
According to the present invention, it is possible to minimize loss of original sound and improve a three-dimensional image feeling. In addition, it is possible to reproduce a lively live sound by reinforcing the reduction in the amount of background sound inevitably generated in the initial mixing process at the time of producing the sound board in the reproduction process. In the technology of the present invention, a circuit configuration is adopted in which reprocessing is performed with emphasis on the channel signal without processing the L + R signal and the LR signal by various circuits as in the prior art described above. Therefore, it is possible to minimize the change of the sound field, reduce the signal-to-noise ratio and THD (Total Harmonic Distortion), reduce the loss of the original sound, and further expand the sound directionality and spatiality, and the feeling of movement. it can.
[0007]
Normally, when playing audio signals on low-priced audio equipment, the quality or performance of amplifiers and speakers is limited, so it is not possible to play beautiful sounds over the low, mid, and high frequency bands. Impossible. However, by applying the present invention, it is possible to remove some restrictions on performance such as amplifiers and speakers. In other words, in the present invention, the gain characteristic is increased with the original signal as the center in the low frequency band, and the original signal and the difference signal are composed of about 50 to 50 in the middle frequency band to express the directionality of the sound and the sense of space. In the high frequency band, which is a region, natural sound is reconstructed by increasing the gain around the difference signal. Therefore, the reproduction characteristics of the acoustic signal can be improved even in a low-end machine that is inevitably restricted by performance.
[0008]
In other words, the system of the present invention has a mutually symmetrical circuit configuration suitable for processing a stereo signal, uses the difference in sound between the left and right channels to increase the spatiality of the sound, and the circuit configuration. It is a new concept surround system that is simplified and prevents degradation of signal-to-noise characteristics, thereby increasing and improving the performance of the device for price.
[0009]
As will be described later, in the present invention, a spatiality substituting unit that extracts a spatial image from the left and right channel signals in terms of frequency, a frequency band reinforcing unit for reinforcing the midrange and low range of the original sound, and a channel The matrix means is the main component.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing a basic configuration (first embodiment) of a frequency selective spatial enhancement system according to the present invention. This system is applied to a processor that creates a three-dimensional image stereo signal from a stereo input signal. As shown in FIG. 1, the system of the present embodiment inputs a left and right input signal (L-in) (R-in) and inputs a spatiality subsidy unit (30) that emphasizes the spatiality and directionality of sound. (40), input signals on the left and right sides, respectively, and the band reinforcement portions (50) and (60) for reinforcing the midrange and low range of the original sound, and the output signals of the spatiality aid portions (30) and (40) The left and right signal lines are provided with channel matrix stages (70) and (80) for performing matrix processing on the output signals of the band reinforcement sections (50) and (60) and the left and right channel signals, respectively.
[0011]
The system of the present invention having such a configuration is configured such that the left and right input signals (L-in) (R-in) are input to each circuit through the buffers (10) and (20). Here, the reason why the buffers (10) and (20) are provided in the signal input line is to increase the impedance on the input side to reduce signal attenuation during signal transmission, and to reinforce signal degradation in terms of frequency characteristics, This is for preventing the signal from being deteriorated by processing the signal of the next stage through various paths.
[0012]
As shown in FIG. 1, the input signals (L-in) and (R-in) pass through buffers (10) and (20), and left and right spatiality substituting units (30) that emphasize the spatiality and directionality of sound. (40) and the band reinforcement units (50) and (60) that reinforce the middle band and the low band of the original main channel signal, respectively. The outputs of these spatiality substituting units (30) and (40) and the outputs of the band reinforcement units (50) and (60) are further input to the left and right channel matrix units (70) and (80). A part of the input signals (L-in) (R-in) is directly input to the channel matrix sections (70) and (80).
[0013]
The spatiality subsidies (30) and (40) generate L ′ and R ′ signals for creating sound directionality and spatiality. Here, the output signal L ′ of the spatial support unit (40) is input to the right side matrix unit (80), and the output signal R ′ of the spatial support unit (30) is input to the left channel matrix (70). LR ′ and RL ′ are respectively calculated.
[0014]
The band reinforcement portions (50) and (60) are for reinforcing the mid-range and low-frequency range of the original channel signal, where signals L "and R" are formed. The L ″ and R ″ signals are input to the left and right channel matrices (70) and (80), respectively, and added to the calculation results of LR ′ and RL ′. That is, the left and right channel matrices (70), (80) are output (L ′), (R ′) of the spatial support sections (30), (40) and outputs (L ″) of the band reinforcement sections (50), (60). ) (R ″) and the main channel signals (L) and (R) are subjected to matrix operation. In the left channel (L-OUT), a signal in the form of L−R ′ + L ″ is transmitted to the right channel ( In R-OUT), a signal of the form RL '+ R "is finally output.
[0015]
Here, the spatial subsidizing sections (30) and (40) have characteristics of a high-pass filter, and the band reinforcement sections (50) and (60) have characteristics of a low-pass filter. By configuring these filters to have a gain close to unity in the midband, if the midband signals are exactly the same on the left and right, L = L ′ = L ″ = R = R ′ = R ". Accordingly, L = R = 1 is output to the left channel (L-OUT) by calculating LR ′ + L ″ and RL ′ + R ″ in the matrix sections (70) and (80), and the right channel. R = L = 1 is output to (R-OUT). If there is a difference between the left and right midband signals, L + (L ″ −R ′) is output to the left channel (L−OUT) and R + (R ″ −L is output to the right channel (R−OUT). ') Has output characteristics. With this configuration, in the middle band, whatever the left and right signals are, the signals are maintained and output as they are.
[0016]
In the low frequency band, the R ′ and L ′ components have a low gain. Therefore, when performing the above calculation of L + (L ″ −R ′) and R + (R ″ −L ′), The main components L + L ″ and R + R ″ are relatively large. Therefore, in the low frequency band, the original channel signal is emphasized and output.
[0017]
On the other hand, in the high-frequency band that affects the spatial feeling and directionality of the sound, the gains of L ″ and R ″, which are the outputs of the band reinforcement units (50) and (60), are small, and the spatiality subsidies (30) and (40). The gains of R ′ and L ′, which are the outputs of, are close to unity. Therefore, in calculating L + (L ″ −R ′) and R + (R ″ −L ′), L−R ′ and R−L ′ become central components, so that the spatial sense and directionality of the sound result. Is increased.
[0018]
That is, in the present invention, the sound frequency band is divided into three equal parts, the main channel signal is reinforced in the low frequency band signal, the main channel signal is maintained as it is in the mid frequency band, and the main channel signal is maintained in the high frequency band. By increasing the subtraction amount, the sound spatial sense and directionality are improved as a whole while balancing the sound over all regions of the low, middle and high frequency bands.
[0019]
FIG. 2 is a diagram showing a detailed configuration of the spatiality promoting part of the frequency-selective spatial improvement system of the present invention, FIG. 2A is a diagram showing a circuit configuration of the spatiality promoting part, and FIG. ) Is the characteristic graph. Spatial support sections are provided in the left and right channels, respectively, and have a circuit configuration for generating R ′ and L ′ signals for emphasizing the spatiality and directionality of the sound and the background sound.
[0020]
The basic concept is that R ′ and L ′ signals are created by selectively passing the signal components corresponding to the high frequency side centered on the audio frequency of each channel signal, and are opposed to each other in the matrix stage. By subtracting this from the signal, the signal of the three-dimensional image component of the sound is derived. General stereo signals have many common components in the left and right channel signals in the mid- and low-frequency bands, and the stereo components that actually separate the sound into left and right and many 3D image components are contained in the high-frequency band. ing. Therefore, in each channel, a signal corresponding to the high frequency region centered on the sound frequency is passed through in a frequency-selective manner and subtracted from the opposing main channel signal to derive a three-dimensional image component signal. .
[0021]
As shown in FIG. 2A, the spatial support unit (40) has a circuit configuration made up of a capacitor (C41) and a resistor (R41), and constitutes a high-pass filter. Here, the gain characteristics of the passband and cut-off frequency bands can be adjusted according to the time constants of the capacitor (C41) and the resistor (R41). Also, the presence and midrange sound can be adjusted according to the time constant. This circuit is provided in order to make R 'and L' components for subtraction from the main channel signal in the matrix circuit in the subsequent stage, and the gain in the middle and high band is set to 1 and cut off in the low band Configure a high-pass filter with frequency. FIG. 2B shows an example of frequency characteristics of the output of the spatiality assisting unit 40.
[0022]
The amount of the three-dimensional stereo image signal can be freely adjusted by adjusting the time constants of the resistor (R41) and the capacitor (C41) constituting the circuit of the spatial support unit 40 shown in FIG. Also, by adjusting the time constants of these elements, it is possible to construct various three-dimensional image forms by adjusting sound spatiality.
[0023]
The resistor (R42) provided after the spatiality subsidizing unit (40) determines the factor of the matrix operation circuit of the right channel matrix (80), and calculates RL ′ + R ″ by the right channel matrix (80). This is for executing the -L 'calculation function.
[0024]
FIG. 3 is a diagram showing details of the band reinforcement unit used in the system of the present invention, FIG. 3A is a diagram showing a circuit configuration of the band reinforcement unit, and FIG. 3B is a graph showing its characteristics. The band reinforcing unit has a function of reinforcing a low-frequency component in the main channel signal attenuated by a subtraction operation (LR ′) performed in the matrix stage, and has a low-pass filter characteristic. Since the above-mentioned R ′ signal component has a gain close to 1 in the mid-range and high-range, the midtone is relatively attenuated when the calculation of (LR ′) is performed. This is a configuration for preventing the components from being lost.
[0025]
As shown in FIG. 3A, the band reinforcing portion 50 includes a resistor (R51) and a capacitor (C51). The cut-off frequency of the low-pass filter is determined according to the time constant of the resistor (R51) and the capacitor (C51). In the present invention, a low-pass filter having a cutoff frequency in the high band is configured. Since the voice band is a 1 kHz band, the voice band and the low band of the main channel signal can be reduced by giving a gain of about 1 in the voice band, that is, the middle band, and having a gain of 1 even in the low band. Can be reinforced.
[0026]
In terms of the circuit configuration, the resistor (R51) and the capacitor (C51) are low-pass filters for reinforcing the mid-range and low-range. A resistor (R52) connected to the left channel matrix (70) after the band reinforcement unit 50 is an operation factor of the L ″ signal component when calculating LR ′ + L ″ in the left channel matrix (70). It is for determining. FIG. 3B shows an example of frequency characteristics of the output of the band reinforcing unit 50.
[0027]
FIG. 4 is a circuit diagram showing a detailed configuration of matrix means used in the system of the present invention. In this matrix circuit, all the addition and subtraction functions of the operational amplifier (U71) are used to add and subtract the main channel signal, the output signal of the band reinforcement unit (50), and the output signal of the spatiality substituting unit (30). I did it. That is, the main channel signal L and the signal L ″ which is the output signal of the band reinforcing unit (50) are input to the non-inverting input (+) of the operational amplifier (U71), and the output signal R ′ of the spatiality promoting unit (30) is input. Input to the inverting input (-).
[0028]
The calculation factor of the left channel matrix (70) is determined by resistors (R71) (R72) (R73) (R74). If these resistors are all set to the same value, the output of the channel matrix (70) becomes L + L ″ −R ′ by the addition / subtraction structural formula of the operational amplifier (U71). Further, the right channel matrix (80 having the same configuration as the matrix (70)). ) Becomes R + R ″ −L ′. That is, the addition / subtraction factors of each signal are all set to 1. Moreover, an appropriate factor can be comprised if the value of resistance (R71) (R72) (R73) (R74) is changed and set according to a use.
[0029]
The optimum value of the matrix addition / subtraction factor differs depending on human listening characteristics when an actual stereo apparatus is operated, and the left output L + L ″ −R ′ and the right output R + R ″ −L ′ of the present invention are an example. Can be seen as. That is, the matrix relational expression can be arranged in various factors depending on the power supply and other application conditions, and can take values other than the above arrangement depending on the situation. Also, the gain factor can be adjusted in the same manner by adding or removing resistors from the matrix circuits (70) and (80).
[0030]
In order to further enhance the effect of spatiality, as shown in FIG. 5, gain adjustment circuits (110a, 110b, 110c) are provided in the subsequent stage of the spatiality substituting part (40) and the band reinforcing part (50) and the channel signal line. May be provided so that the mutual gain between the output of the spatiality substituting unit (40), the output of the band reinforcing unit (50), and the channel signal can be adjusted from the outside. Alternatively, instead of this configuration, as shown in FIG. 6, a variable resistor (R75) may be provided in the matrix circuits (70) and (80) to adjust the mutual gain from the outside. In this way, by providing a gain adjustment element in front of the matrix circuits (70) and (80), or adjusting the resistance of the matrix circuit, the outputs of the spatiality assisting unit (40) and the band reinforcing unit (50), If the mutual gain with each channel signal can be adjusted from the outside, a higher quality sound can be obtained by adjusting the gain of each band as appropriate according to the state of the listening sound or the state of peripheral devices such as the power supply. Can be obtained.
[0031]
FIG. 7 is a graph showing the operation of the entire system of the present invention by the frequency-gain characteristics of each signal. Here, an explanation will be given by taking the calculation performed in the left channel matrix (70) as an example.
[0032]
FIG. 7A is a graph showing the frequency characteristics of the left channel signal (L) which is the main signal. The signal L passes through the buffer (10) and is input to the band reinforcement unit 50 and the matrix unit 70 as they are. This signal L has a signal characteristic with a gain of 1 over the entire audible frequency band.
[0033]
FIG. 7 (b) is a graph showing the frequency characteristics of the output signal L ″ of the band reinforcement unit (50), that is, the low-pass filter. This signal has a gain of 1 in the middle band and the low band, and is 10 kHz. With the above, there is a characteristic that the gain gradually decreases.
[0034]
FIG. 7C is a graph showing the frequency characteristics of the output signal R ′ of the spatiality assisting unit (30). This signal R ′ is for extracting a frequency component of the middle and high frequency band or more from the right channel signal of the main channel signal and subtracting it from the left channel signal of the main channel in the left matrix section (70) at the subsequent stage. The spatial subsidizing section (30) has a high-pass characteristic with a pass band of about 100 HZ or higher, and therefore, this signal R ′ has a frequency characteristic with a gain of about 1 in a band of 100 HZ or higher.
[0035]
The spatial support part (30) and the band reinforcing part (50) are configured such that the resistance value can be varied from the outside so that the cutoff frequency can be adjusted arbitrarily by changing the time constant of the filter. Good. Moreover, when producing in large quantities, a time constant can also be fixed.
[0036]
FIG. 7D is a graph showing the frequency characteristics of the common component of the left and right channel signals. As shown in FIG. 7D, the common component of the left and right channel signals includes many signal components in the low band including the audio band, that is, the mid band. In other words, because of the characteristics of a general stereo sound source, there are many common components distributed in both the left and right channels in the audio band and the low band, and therefore this band often has the character L = R. Since the final arithmetic expression of the left channel matrix (70) is L + L ″ −R ′, if L = R = 1 is substituted here, L = L ″ = 1 in the low band, and the distribution of the R ′ signal becomes small. As a result, the gain becomes 2 in the low frequency range, and becomes gradually smaller. Further, since L = L ″ = R ′ = 1 in the middle region, the value of gain 1 can be almost maintained.
[0037]
By configuring in this way, the original channel signal is emphasized in the low frequency range to reproduce the sound. In the mid frequency range, there are some gain differences depending on the similarity of the left and right channel signals, but the mid frequency range That is, the gain of the audio signal component can be maintained. In other words, the low frequency of the original channel is emphasized and reproduced, and the effect of maintaining the mid-range sound as it is can be achieved at the same time.
[0038]
FIG. 7 (e) is a frequency characteristic diagram of the output characteristics of a signal in the high frequency band, that is, the difference component between the left and right stereo signals, which influences the spatial area. In general, the area for recognizing the spatial feeling or directionality of a sound in the characteristics of a stereo sound source or the auditory characteristics of the ear is in the middle and high bands. Here, the final calculation formula of the matrix stage is L + L ″ −R ′, and as described above, since there are many common components in the mid-band, assuming that L = L ″ = R ′ = 1, the calculation result is almost 1. The middle range, that is, the voice range is maintained as it is. On the other hand, in the high frequency band, since the L ″ component of the output of the band reinforcement unit is small, the signal component is mainly composed of a difference component between the channel signal L and the output R ′ of the spatial support unit, an LR ′ component. Therefore, the ratio of the difference component in the high frequency band, which is the area that determines the spatial feeling or directionality of the sound, while maintaining the middle area, that is, the central part of the sound, is increased. The effect of expanding the background sound can be derived.
[0039]
In the present invention, as a result, the original sound (speech range) is maintained and enhanced in the middle and low ranges, and the spatial feeling of the sound is expanded in the middle and high ranges and the original sound (speech range). ) Can be maintained, and an ideal coupling can be obtained that balances over the entire frequency band and at the same time expands the sound field.
[0040]
FIG. 8 is a block diagram showing the overall configuration of the second embodiment of the system according to the present invention. As shown in FIG. 8, in the second embodiment, after the gain of the entire system is increased by the matrix stages (70) and (80), the band reinforcement sections (90) and (100) are added to the subsequent stages of the matrix stages (70) and (80). ) To reinforce a specific frequency band.
[0041]
FIG. 9 is a block diagram showing the configuration of the latter stage of the matrix stage of the second embodiment of the system according to the present invention. FIG. 9A is a diagram showing a detailed circuit configuration of this band reinforcing portion, and FIG. 9B is a graph showing its characteristics. With the matrix operation performed in the matrix stages 70 and 80, sound reproduction processing with a sense of reality can be performed while appropriately balancing the sound over the low, medium, and high frequencies. In this example, for example, A second band reinforcement unit (90) is provided at the subsequent stage of the matrix so that it can be used with specific software that is used with movie software and emphasizes low frequencies, and is filtered again to the signal processing results at the matrix stage. A specific frequency band is reinforced by processing. Various circuits can be applied to the second band reinforcing portions (90) and (100). It can also be configured by a passive circuit composed of a resistor and a capacitor as shown in FIG. 9A, or an active circuit composed of an operational amplifier and a passive element.
[0042]
In the second embodiment of the present invention, the second band reinforcing portion (90) is constituted by a passive filter including resistors (R91) and (R92) and a capacitor (C91). The configuration of the band reinforcing part (100) of the right channel is the same. As can be seen from the characteristic graph shown in FIG. 9B, according to this filter configuration, the gain in the passband is 1 and the gain in the cutoff band is R92 / (R91 + R92). If the gain factor is increased and then output is made through the band reinforcement sections (90) and (100), the low band can be reinforced, and the gain of the mid band and the high band can be adjusted. Further, if necessary, an active circuit can be configured to independently adjust the gain characteristics of a specific band.
[0043]
FIG. 10 is a diagram showing the configuration of the third exemplary embodiment of the system according to the present invention. In the third embodiment, in order to simplify the circuit, signals from the left and right channels are input to the channel matrix (70) (80) without providing the band reinforcement sections (50) (60), and gain is obtained. The entire circuit is configured so as to replace the band reinforcing portions (50) and (60). However, the circuit role of the spatiality subsidies (30) and (40) is the same as other examples.
[0044]
In the overall operation of the system of the present invention, the original channel signal is emphasized in the low band, the original signal is maintained in the middle band, and the presence and directionality are further increased in the high band. The effect can be obtained at the same time. If necessary, a specific band can be reinforced according to the type of the original sound. The present invention can be applied to any apparatus that reproduces the sound of a three-dimensional image from a stereo signal. Further, the system of the present invention can be applied not only when reproducing an acoustic signal but also when recording.
[0045]
【The invention's effect】
According to the present invention, an optimal three-dimensional stereophonic sound can be obtained by appropriately providing a circuit for the original stereo signal. According to the surround circuit system of the present invention, it is possible to expand the sense of space while maintaining the sound of a specific band. Furthermore, the effect of reproducing the background sound that could not be seen in the conventional surround system can be obtained, and the dynamic range of signal reproduction can be enhanced according to the filter curve characteristics.
Using the above standard circuit, the sound field effect and the background sound expansion effect that match various conditions of the sound source are obtained by slightly adjusting the time constant of the elements constituting the circuit according to the application situation. Can do.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a basic configuration (first embodiment) of the present invention.
FIG. 2 (a) is a detailed circuit diagram showing a configuration of a spatial support unit of the present invention, and FIG. 2 (b) is a characteristic graph thereof.
FIG. 3 (a) is a detailed circuit diagram showing the configuration of the band reinforcing portion of the present invention, and FIG. 3 (b) is a characteristic graph thereof.
FIG. 4 is a detailed circuit diagram showing a configuration of a matrix section of the present invention.
FIG. 5 is a diagram showing a modification of the system of the present invention shown in FIG.
6 is a diagram showing another modification of the system of the present invention shown in FIG. 1. FIG.
FIG. 7 is a diagram showing the frequency characteristic gain of the system of the present invention.
FIG. 8 is a circuit diagram showing an overall configuration of a second embodiment of the present invention.
FIG. 7A is a detailed circuit diagram showing a second embodiment of the present invention, and FIG. 7B is a characteristic graph thereof.
FIG. 10 is a diagram showing a configuration of a third exemplary embodiment of the present invention.
[Explanation of symbols]
10,20 buffers
30, 40 Spatial subsidy department
50,60 Band reinforcement
70 Left channel matrix
80 Right channel matrix
90,100 Bandwidth enhancement unit

Claims

In a system that creates a 3D image stereo signal by inputting a stereo signal, a spatial support unit that enhances the spatiality and directionality of the sound by inputting the channel signal, and a predetermined frequency band is enhanced by inputting the channel signal. The frequency of each of the left and right signal lines includes a band reinforcement unit for maintaining and maintaining, an output signal of the spatial support unit, an output signal of the band reinforcement unit, and channel matrix means for performing a matrix operation on the channel signal. In the selective spatial enhancement system, the spatiality subsidy section has a high-pass filter characteristic having a cut-off frequency in the low-frequency band, and improves the spatiality and directionality of the left and right sounds, A frequency selective spatial enhancement system characterized by acting to maintain.

In a system that creates a 3D image stereo signal by inputting a stereo signal, a spatial support unit that enhances the spatiality and directionality of the sound by inputting the channel signal, and a predetermined frequency band is enhanced by inputting the channel signal. The frequency of each of the left and right signal lines includes a band reinforcement unit for maintaining and maintaining, an output signal of the spatial support unit, an output signal of the band reinforcement unit, and channel matrix means for performing a matrix operation on the channel signal. In the selective spatial improvement system, the frequency band reinforcing part has a low-pass filter characteristic having a cut-off frequency in the high band, and functions to reinforce the low band of the original signal and maintain the mid band. A frequency-selective spatial improvement system characterized by:

3. The frequency selective spatial improvement system according to claim 1 or 2, wherein the channel matrix portion has an output of the left channel matrix portion of αL + βL ″ −γR ′ and an output of the right channel matrix means of αR + βR. The signal L ”and the signal R” have a low-pass characteristic, L ′ and R ′ have a high-pass characteristic, and α, β, γ. Each frequency factor can be arbitrarily set according to the application, and the frequency selective spatial feeling improving system is characterized.

4. The frequency selective spatial feeling improving system according to claim 1, wherein the system further includes a second band reinforcing portion for reinforcing a specific frequency band of the output of the matrix means on the left and right signal lines. A frequency-selective space improvement system characterized by comprising each.

In a system that creates a 3D image stereo signal by inputting a stereo signal, a spatial support unit that enhances the spatiality and directionality of the sound by inputting the channel signal, and a predetermined frequency band is enhanced by inputting the channel signal. The left and right signal lines are each provided with a band reinforcing unit for maintaining the output, the output signal of the spatial support unit, the output signal of the band reinforcing unit, and channel matrix means for performing a matrix operation on the channel signal. And a spatial frequency enhancement system comprising gain adjusting means for adjusting mutual gains between the output signal of the spatiality promoting means, the output signal of the frequency band reinforcing means, and the channel signal. The part has a high-pass filter characteristic with a cut-off frequency in the low-frequency band, and improves the spatial and directivity of the left and right sounds Frequency selective spatial sense enrichment system, characterized in that acts to maintain the midrange signal.

In a system that creates a 3D image stereo signal by inputting a stereo signal, a spatial support unit that enhances the spatiality and directionality of the sound by inputting the channel signal, and a predetermined frequency band is enhanced by inputting the channel signal. The left and right signal lines are each provided with a band reinforcing unit for maintaining the output, the output signal of the spatial support unit, the output signal of the band reinforcing unit, and channel matrix means for performing a matrix operation on the channel signal. And a frequency selective spatial enhancement system comprising gain adjusting means for adjusting a mutual gain between the output signal of the spatiality assisting means, the output signal of the frequency band reinforcing means, and a channel signal. Has a low-pass filter characteristic with a cut-off frequency in the high band, reinforcing the low band of the original signal and Frequency selective spatial sense enrichment system, characterized in that acts to lifting.

7. The frequency selective spatial improvement system according to claim 5 or 6, wherein the output of the left channel matrix portion is αL + βL ″ −γR ′ and the output of the right channel matrix means is αR + βR. A frequency characterized by having a characteristic of “−γL ′, wherein the signal L” and the signal R ”have a low-pass characteristic, and L ′ and R ′ have a high-pass characteristic. Selective space improvement system.

8. The frequency selective spatial feeling improving system according to claim 5, wherein the system further includes a second band reinforcing portion for reinforcing a specific frequency band of the output of the matrix means with left and right signal lines. A frequency-selective spatial improvement system characterized by comprising

9. The frequency selective spatial improvement system according to claim 5, wherein the gain adjusting means has a large gain in a low frequency with respect to a common component of left and right stereo signals, and the signal in a mid frequency range. The mutual gain of each signal is adjusted so that it has the characteristic of maintaining the component as it is, and for the difference component of the left and right stereo signals, the gain is high in the high range and the signal component is maintained in the mid range This is a frequency selective spatial improvement system.

Spatiality assisting means for deriving a component that enhances spatiality and directionality from a channel signal in a frequency selective spatial enhancement system applied to a device that converts a stereo input signal into a three-dimensional image stereo signal and records it; A channel matrix for performing a matrix operation on a frequency band reinforcing means for reinforcing and maintaining a specific frequency band of the channel signal, an output signal of the spatiality assisting means, an output signal of the frequency band reinforcing means, and the channel signal In the frequency-selective spatial feeling improving system, the left and right signal lines each having a means, the spatiality promoting unit has a high-pass filter characteristic having a cut-off frequency in a low band, and A frequency selective sky characterized by increasing spatiality and directionality and acting to maintain mid-range signals Feeling improvement system.

Spatiality assisting means for deriving a component that enhances spatiality and directionality from a channel signal in a frequency selective spatial enhancement system applied to a device that converts a stereo input signal into a three-dimensional image stereo signal and records it; A channel matrix for performing a matrix operation on a frequency band reinforcing means for reinforcing and maintaining a specific frequency band of the channel signal, an output signal of the spatiality assisting means, an output signal of the frequency band reinforcing means, and the channel signal In the frequency-selective spatial enhancement system, which includes means for the left and right signal lines, respectively, the frequency band reinforcement unit has a low-pass filter characteristic having a cutoff frequency in the high band, Frequency selective spatial feeling improvement system characterized by acting to reinforce the region and maintain the middle region .

12. The frequency selective spatial improvement system according to claim 10 or 11, wherein the channel matrix portion has an output of the left channel matrix portion of αL + βL ″ −γR ′ and an output of the right channel matrix means of αR + βR. The signal L ”and the signal R” have a low-pass characteristic, L ′ and R ′ have a high-pass characteristic, and α, β, γ. The frequency selective frequency selective spatial feeling improving system characterized in that each factor of can be arbitrarily set according to the application.

13. The frequency selective spatial feeling improving system according to claim 10, wherein the system further includes a second band reinforcing unit that reinforces a specific frequency band of an output of the matrix means with left and right signal lines. A frequency-selective spatial improvement system characterized by comprising

14. The frequency-selective spatial enhancement system according to claim 1, wherein channel buffers are respectively provided in the preceding stage of components that perform a process of producing a stereoscopic effect on the left and right signal lines. A frequency selective spatial improvement system.